Fossil fuels, such as coal, oil, and natural gas are non-renewable energy sources and their ever-increasing consumption leads to excessive emission of greenhouse gases, and in particular carbon dioxide (CO2). To mitigate negative consequences of fossil fuel use, methods for reduction of carbon emission have been implemented, but with marginal success. Concern over fossil fuel use has also led to global development and implementation of renewable energy sources over the past decades. Renewable energy sources such as wind and solar are increasingly harvested to generate electricity, but the intermittent nature of these sources requires the capacity for large-scale energy storage.
Co-electrolysis of steam and carbon dioxide by use of solid oxide electrolysis cells (SOEC) is a promising energy storage method that can efficiently transform electrical energy into syngas (a mixture of H2 and CO), which can be stored and converted back to electricity at a later time or can be used as feedstock for chemical synthesis. Unfortunately, there are still major challenges for large scale deployment of SOECs. One principal challenge is that a significant portion of energy input is required to overcome the large oxygen potential gradient (e.g., open circuit voltage up to 1.0 V) in the electrolysis process because the anode is often exposed to air, which has a high oxygen partial pressure. Reducing the oxygen partial pressure at the anode and the resulting lowering of the open circuit voltage (OCV) is desirable. Utilizing oxygen produced at the anode would also be beneficial in further improving system efficiency.
Carbon gasification (CG) is a known process used to transform carbon-containing solids (such as coal and biomass) into gaseous fuels such as CO, H2, and CH4. It has emerged as a clean and effective way for the production of gaseous fuels that can be used for power generation or synthesis of chemicals.
What are needed in the art are efficient energy storage technologies to improve use of renewable energy sources and decrease carbon emissions.